Contactor safety combinations are known as electrical circuit arrangements. Most conventional contractor safety arrangements are composed of three auxiliary contactors or relays. As shown in FIG. 8, the position of contactors K2 and K3 is queried via a pre-contactor K1 before the closing operation. In trouble-free operation, the enabled circuit, composed of the series connection of the break-contact element K1, the make-contact element K2 and the make-contact element K3, is enabled by the break-contact element K1. Even in the event of a malfunction, reliable circuit-breaking is ensured due to the series connection of the make-contact elements K2 and K3. The reliability of these designs is guaranteed by an electrical interlock and position query, respectively, of contactors K1, K2 and K3. Characteristic of this specific embodiment is a high expenditure of time and energy for circuit wiring. To avoid wiring errors, the main portion of the necessary wiring is provided via a printed-circuit board. The quality of the enabling conducting path on the printed-circuit board determines the permissible current. In conventional contactor safety combinations, this lies below the permissible current of the individual contactors.
German Patent Application No. 24 40 361 describes a conventional interlocking module which interconnects two contactors using their operating heads. In this case, the interlocking module is not used as a reclosing lockout in the fault condition of one of the two contactors, but rather to ensure that during the normal operation in the "ON" switching state of the one contactor, as the result of positively driven operation, the other contactor is in the "OFF" switching state.
Furthermore, German Pat. application Ser. No. 36 02 692 describes a reclosing lockout of a relay. Realized here is the reclosing lockout of a relay switching two contact arrangements simultaneously using a switching finger. A shared contact element, on which a pointer is formed, engages with the two movable contacts of the contact arrangements. The free end of the pointer lies in the track of travel of the switching finger when both movable contacts are in the same position. The pointer and the switching finger are so narrow that the actuating surface of the pointer lies outside of the track of travel of the switching finger when the contact element is tilted because the two movable contacts are in a different position, i.e. when one of the contacts sticks.